Control apparatus for centralized traffic control systems of the code type for single track railroads



April 17, 1951 H. s. YOUNG CONTROL APPARATUS FOR CENTRALIZED TRAFFIC CONTROL SYSTEMS OF THE CODE TYPE FOR SINGLE TRACK RAILROADS 15 Sheets-Sheet 1 Filed May 9, 1946 INVENTOR.

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CONTROL APPARATUS FOR CENTRALIZED TRAFFIC CONTROL SYSTEMS OF THE coma TYPE FOR SINGLE TRACK RAILROADS 3 Sheets-Sheet 2 Filed May 9, 194

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Patented Apr. 17, 1951 CONTROL APPARATUS FOR CENTRALIZED TRAFFIC CONTROL SYSTEMS OF THE CODE TYPE FOR SINGLE TRACK RAIL- ROADS Henry S. Young, Wilkinsburg, Pa., assignor to The Union Switch & Signal Company, Sw1ssvale,Pa., a corporation of Pennsylvania Application May 9, 1946, Serial No. 668,363 14 Claims. (Cl. 246-3) My invention relates to railway trafiic controlling apparatus, and more particularly to an improved system of circuits for use in centralized traffic control machines for the remote control of traffic movements in either direction on single track railroads. and is an improvement upon that shown in Fig. 1 of my application for Letters Patent of the United States, Serial No. 501,25i filed September 1943, for Railway Traffic Controlling Apparatus, which issued as Patent No. 2,420,579, on May 13, 1947.

My invention is particularly adapted for use in a centralized traffic control system for manually controlling the signals of an absolute permissive block signaling system in which the signals are also governed automatically in accord ance with traffic conditions by a system of reversible line circuits, controlled by continuous track circuits, as disclosed in my prior application above referred to. In systems of this char acter, the movement of trafiic in either direction into a single track block is governed by head block signals, located at opposite ends of the clocks, and these blocks are divided into block sections, with intermediate signals for the two directions located at the junctions of the sections, all of which are controlled over a system of reversible line circuits in accordance with traiilc conditions as manifested by the track relays of the sections in advance of the signals. Other opposing head block signals govern traffic move ments into, blockswhich include passing tracks, where only the main track is provided with track circuits for controlling the signals, and since these blocks are relatively short, separate line circuits are provided for the two directions.

All of the head block signals are subject to manual control from a central point, such as a train dispatchers office, by the provision of a code type communication system having field stations adjacent the track switches at the ends of the passing tracks for receivin control codes transmitted from the ofiice, by which control relays for the switches and signals are operated in accordance with the positions of switch and signal levers at the office, and by which trafiic relays are operated to govern thedirection of en ergization of the reversible line circuit system for each single track block in accordance with the position of a master directional relay at the ofllce. The station apparatus of thecode system also serves to transmit indication codes to the omce for indicating wayside conditions to the operator by lighting various lamps associated with a track diagram, and for imposing restrictions upon the issue of control codes bythe operator.

The centralized traffic control system also includes provisions for releasing electric locks for v outlying hand throw switches by cooperation between the central ofiice operator and the crew of a train.

One object of my invention is the provision of an improved system of traffic direction control for use in the centralized traffic control system referred to, or in other systems having generally similar requirements such as those employing cascade connected reversible track circuits in place of line circuits, as shown, for example, in Letters Patent of the United States, No. 2,344,333, issued March 14, 1944, to James J. Van Horn, for Railway Traffic Controlling Apparatus.

A feature of my invention is the provision of a signal clearing stick relay at the oifice for each head block signal for governing the transmission of control codes for clearing the signals, which relays are electrically interlocked to prevent the issue of signal clearing codes except when conditions are proper.

The traffic direction controlling apparatus of my invention functions in such a manner that the control of the traffic relays at the ends of the blocks requires no special action of the operator, but is effected automaticallyas a result of the usual operations for clearing a code controlled signal, these comprising the reversal of the signal lever for the head block signal which is to be cleared, followed by the operation of the associated code starting button whereby the trans,- mission of a code for clearing the signal is initiated. In the event a' reversal of trafiic direction is required in order to permit the signal to clear, these operations result first in the movement of a master directional relay at the control oifice to a position designating the desired trafiic direction, and then in the transmission of control codes to both ends of the block whereby the intermediate signals for the original trailic direction are put to stop, and then the intermediate signals for the desired direction are cleared automatically as the line circuit system becomes energized section by section. The control code received at the entering end of the block also operates a signal control relay thereby causing the head block signal at that end to clear in response to the energization of the line circuit system.

A feature of my invention resides in the control of the apparatus for reversing traflic, as above described, by a signal clearing relay, identified with the entering head block signal, in such a manner that this apparatus becomes looked upon the issue or a slgnai clearing code, and then remains locked until indication codes are received \NlilUll 1nd1cate that the block is unoccupied and that the head block signals are at stop.

Another feature of my invention involves the control of the signal indication relays so that they not only indicate the condition of the signals but also the condition of approach locking relays controlled thereby, by which the signals are electrically interlocked with the track switches and with the opposing signals at the distant end of the block, whereby the control of the traffic direction apparatus. is made de-' pendent upon the approach and time locking conditions in the field as reflected by these relays.

A further feature of my invention is the provision of a signal clearing relay for each leaving signal at the end of a single track block, for

: governing traffic movements into one of the adoining passing tracks.

This relay serves to prevent the inadvertent clearing of the leaving signal by a control code transmitted to its station when the code is initiated by the operation of the starting button for the entering signal at the opposite end of the block.

Another feature of my invention comprises an improved arrangement for unlocking a hand throw switch at an outlying location within the block by the transmission of control codes to both ends. These codes may be initiated by the operation of a control lever for the switch only when the entering signals at the ends of the block are at stop, and these codes are rendered incapable of clearing the entering signals even though the signal levers are inadvertently reversed before they are transmitted.

Other objects, purposes and features of my invention will be pointed out as the description proceeds.

I shall describe one form of apparatus embodying my invention, and shall then point out the novel features thereof in claims.

Referring to the accompanying drawings, Fig. 1 shows the control levers and circuits embodying my invention. contained in one section of the ofrice control machine of the centralized traffic control system, including the control panels for two stations located at opposite ends of a single track block as indicated by the miniature track diagram at the top of the view. Fig. 1 also shows the control apparatus for the right-hand end of the double track block, extending to the i left, as well as that for the left-hand end of the double track block at the right of the single track block shown, it being understood that the operators control board is made up of a plurality of sections each generally similar to Fig. 1.

Figs. 2A and 2B show a plan of the stretch of railway track corresponding to Fig. 1, together with the wayside circuits and apparatus. The wayside circuits as shown correspond generally to those of Figs. 2A, 2B and 20 of my prior application hereinbefore referred to, but as here shown they are arranged. in a condensed form and the circuits for the control of the track switches IW and 3W'are omitted, since these have no bearing on the present invention.

To simplify the drawings, in lieu of showing the various sources of current for energizing the relays, I have shown only their terminals, the positive or supply terminal being identified by the reference character B and the negative or com- 4 mon return terminal by the reference character C, in each instance. A number of the relays shown, and the signal mechanisms as well, are of the polarized type, operable to different positions in accordance with the relative polarity of the current in their windings, and it is to be oerstood that each such device as shown is so polarized that its left-hand contacts close when terminal B is applied to the left-hand terminal of its winding.

Similar reference characters refer to similar parts in each of the views.

Briefly described, my invention relates to apparatus for governing the operation of central ized trafiic control systems of the code type, for single track railroads, the primary purpose of which is to prevent improper manipulation due to the unavoidable lapse of time between the issue of controls and the reception of return indications. My invention is embodied in apparatus at the control ofilce interposed between the operators levers and the conventional code transmitting apparatus, and includes a signal clearing relay LM or RM for each lever for a signal governing movements into a single track block, a corresponding relay LG or RG for each lever for a signal governing movements outof a single track block, and a repeating relay WLP for each lever for controlling the operation of an outlying track switch. These relays are interlocked one with another so as to prevent the issue of conflicting controls, and the relays LM and RM govern a traffic direction control relay LP, employed conventionally in systems of this character, in a more positive manner than heretofore. due in part to the fact that these relays are controlled not only by their respective signals and the adjacent track relays but also by the signal control relays LHS or RHS and by approach or time looking relays LAS and RAS at the field stations. Additionally, the relays LM and RM, and also the relays LG and RG, function in such a manner as to insure against the inadvertent clearing of their respective signals under various conditions.

The code control system The code system employed for communication between the oifice and the wayside stations corresponds generally to that shown in Letters Patent of the United States No. 2,229,249, issued January 21, 1941, to Lloyd V. Lewis, for Remote Control Systems, and specifically to a modification thereof described in Letters Patent of the United States No. 2,411,375, issued November 19, 1946, to Arthur P. Jackel, for Remote Control Systems, and in a booklet entitled Time Code Control System, Manual 506-A, published by the Union Switch and Signal 00., of .Swissvale, Pa.

Consideration of the detailed mode of operation of the code system is not needed for an understanding of my invention, and it is deemed sufiicient to point out that the code system provides seven channels for the transmission of controls from the office to a selected station, and seven other channels for the transmission of indications from any station to the oflice, only one station at a, time, over a single line circuit, without interference. For simplicity, the various channels are designated by numbers and are represented herein by direct wire connections. Each 7 control code transmitted from the ofiice is initiof which one is provided for each oiiice panel.

Each starting relay is picked up by the momentary closing of a contact a or b of a starting button ISTB or 3STB or of the switch lock lever ZWL. Lever ZWL is of the push-turn type, its contacts a and 2) closing whenever its rotary contacts c and d are moved from one operative positive to another. Each starting relay initiates a code by closing its front contact 0, to pick up the master relay GM of the code system, by which the transmission of the code is governed, and is held energized over a stick circuit until its code is transmitted, in the manner described in Patent No. 2,229,249.

Each control code includes a distinctive code call by which a selector relay OiS or 03$ for the same panel, together with a delivery relay ID, Fig. 2A, or relay 3D, Fig. 23, at the corresponding field station No. 1 or No. 2, are energized, only one panel and station at a time, thereby establishing the control channels for communication between the selected panel and station. Atthe oilice each channel is supplied with current or not, depending upon the control to be effected, and at the selected station a group of polar stick relays comprising a traflic relay ZRFS or dLF-S, a switch lock control relay ZWLS, and the signal control relays ARI-IS and ZLI-IS or dRHS and 4LI-IS, and other similar relays, not shown, are operated to normal or reverse in accordance with the condition of a series of register relays IFZ, IF4, etc., interposed in the channels. Of the seven control channels which the system provides, only channels 2, 4, 5 and I are shown herein.

The master directional relay by which the direction of trafiic movements in the single track block is governed is relay LP, Fig. 1. At stations No. 1 and No. 2, respectively, the traific relays ZRFS and 4LFS are operated over channel 2 by different codes to a position corresponding to that of relay LP. At station No. 1, the switch lock control relay ZWLS for the hand throw switch 2W is controlled over channel 4, by a repeating relay ZWLP for the switch lock lever ZWL of Fig. l, relay ZWLP also controlling the traffic relay 4138 over channel 2, in response to a code initiated by the operation of lever ZWL. When relay ZWLP is in its released position, if

contact of relay LP is in its left-hand position as shown, it connects terminal B over back contact 7 of a. direction locking relay LPS and contact e of the selector relay 01s to channel 2 to energize relay IFZ, Fig. 2A, so that when the delivery relay 1D is energized, relay ZRFS is operated over front contacts of relay IF2 to close its left-hand contacts. Since channel 4 is open, relay ZWLS is operated over back contacts of relay IFA to also close its left-hand contacts. Relay 3P2, connected to channel 2 at station No. 2 is not energized by the code transmitted to that station because the connection from terminal B at contact 0 of relay LP over back contact 7c of relay LPS and contact e of relay 038 to channel 2 is open, consequently when the delivery relay 3D is operated, relay ALF-S is energized in the normal direction to close its lefthand contacts. On the other hand, when contact c of relay LP is in its right-hand position, relay IF! is released and relay 3P2 is energized, so that relays ZRF S and 4LFS are operated to close their right-hand contacts by their respective delivery relays ID and 3D.

When relay ZWLP is energized, relay ZRFS will be operated to a position corresponding to that of relay LP as above described, but since terminal B at contact a of relay 2WLP is connected over contact e of relay 038 to channel 2, relay 3F2 is energized and relay lLFS is operated to close its right-hand contacts regardless of the position of relay LP. Also terminal B at contact b of relay EWLP is connected over contact h of relay OIS to channel 4 to energize relay lF- l, causing relay ZWLS to be operated to close its right-hand contacts in response to the code received at station N 0. l.

The head block signals are controlled primarily by the three position signal levers 25G and 486, which levers, by means of their contacts a and b also control relay LP. The signal controls are transmitted over channels 5 and l, and to properly correlate the controls for the entering sig nals for the single track block with the trafiic direction apparatus and to interlock these controls with those for the hand throw switch and for the leaving signals at the same station, a pair of signal clearing relays 'ERM and lL-M is provided. a

To transmit a control code for clearing signal fiLA or lLB, the contacts of relay LP must occupy their left-hand position corresponding to the right-to-left traffic direction. If lever ESG is moved to its left-hand reverse position and the starting button 3STB is operated under this condition, the starting relay 038T is energized over contact a of button 3STB to initiate a control code by which relays OM and 03S at the office and relay SE at station No. 2 are energized. Re lay 03S completes a circuit from terminal -B at front contact h of relay OM over back contact cl of relay 2WLP, the left-hand contact at of relay LP, front contact at of relay 03S, contact 0 of lever 38G, back contact b of relay iRG through relay GLM to terminal C at back contact 6 of relay 3TK, and relay lLM picks up to complete a stick circuit over its front contact a which extends to terminal B at back contact at of relay Z- lZ.

Channel 5 is energized over the connection from terminal 13 at the left-hand contact c of relay LP, back contact of relay 2-42, front contact e of relay 4LM, the left-hand contact d of lever lSG and contact I of relay 03S, whereby relay 3F5, Fig. 2B, is energized and when relay 3D is operated, the signal control relay 4LHS is energized in the reverse direction, closing its right-hand contacts to complete circuits for clearing signal 4LA or dLB, depending upon the position of switch 3W, as hereinafter explained.

To transmit a control code for clearing signal ERA or 2R3, the contacts of relay LP must occupy their right-hand position corresponding to the left-to-right traffic direction, and if lever ZSG is then moved to it right-hand reverse position and the starting button ISTB is operated, the starting relay 0! ST is energized over contact a of button ISTB to initiate a control code by which relays OM and OIS at the office and relay ID at station No. l are energized. Relay OIS completes a circuit to pick up relay ERM extending from terminal B at front contact h of relay OM over back contact at of relay ZWLP, the righthand contact d of relay LP, contact at of relay 01S, contact c of lever 28G, back contact b of relay 211G through relay L'RM to terminal C at contact e of relay ITK, and relay ZRM completes a stick circuit extending to terminal B at back contact b of relay 2-4Z.

In this code, channel I is energized over connection from terminal B at the right-hand contact c of relay LP, back contact e of relay 7 2-42, front contact e of relay ZRM, the righthand contact (1 of clever 286 and contact ,g of

relay OiS, whereby relay lFl, Fig. 2A, is ener- 2W, and also opens a back contact e in the sircuit for the associatedrelay ELG or :ZRG which governs the clearing of the opposing head block signal at the same station. Relay 2RM or iLM when energized also opens its back contact b in the circuits for relay LP and LPS to insure that these relays will be locked deenergized from the time the operator issues a signal clearing code until relay LP becomes locked by the resulting change in trafiic conditions, as occurs when a train accepts the cleared signal and enters the single track block to cause the transmission of indication codes by which relays 3TK, 4LBK, 2RBK and ITK are energized as hereinafter explained. Accordingly, relay ZRM or AIM is arranged to :be released automatically by the track indication relay ITK or 3TK in response to the indication code transmitted when the train governed by the signal which relay ZRM or lLM controls enters the first track section of the block.

The release relay 2- l2 is provided to enable relay 2RM or iLM to be released manually, by the transmission of a signal stop code, by which relay ZRHS or 4RI-IS is restored to its normal position. Assuming for example that while relay GLM is energized, the operator restores the corresponding signal lever 4SG to normal and presses button 3STB to initiate a control code, the selector relay 03S is operated and relay MBP releases momentarily to pick up relay 2-42 over the circuit extending from terminal B at back contact a of relay MBP, contact of relay 03S, contact g of lever 486 and contact 6 of relay 4LM through relay 2- 12 to terminal C. Relay 1 2-42 may also be picked up by restoring lever ZSG to normal and operating button lSTB, while relay 2RM is energized, as will be clear from the drawings. Relay M8M is a normally energized relay controlled by relays O8 and OM of the code system, and is released only during the eighth step of a control code, that is to say, during a step immediately preceding the serie of steps during which the control channels are established,'and serves also to release the energized starting relay O3ST or OIST. Relay 2-42 is held energized over a stick circuit including contact e of relay EZRM or ALM, the signal lever contact g and its own front contact a or c, and by closing its front contact b or d, relay 2-42 extends the stick circuit for the energized relay 2RM or 4Ll /I to terminal B at the back contact h of the associated delivery relay OID or 0 3D. Relay ZRM or lLM is thereby placed under con trol of the code indication system and is released, as hereinafter explained, only upon the reception of a code which indicates that the corresponding signal control relay iLl-IS or ERHS has been restored to normal and that the signals controlled thereby are at stop and are not approach locked so as to prevent a change in route.

When relay 2RM or 4LM releases, its contact e opens the circuit for relay 2-42 so that relay 2-42 also releases.

In the event the operator is unable to release relay 2LM or 4RM by the operation of relay.

(ill

2-42 as above described, he may release relay 2-42 by reversing the signal lever as required to reestablish the original route, the lever contact 9 being included in the stick circuit for relay 2-42 as well as in its pick-up circuit, for that purpose.

The circuits above described including the signal clearing relays ZRM and ELM and the release relay 2-42 is an improvement upon those for a generally similar purpose disclosed in an application for Letters Patent of the United States, Serial No. 592,947, filed May 10, 1945, by Frank T. Pascoe and Arthur L. Jerome, For Trafiic Direction Control Apparatus for Use in Centralized Traffic Control Systems for Single Track Railroads, which has issued as Patent No. 2,528,073, dated October 31, 1950.

The signal clearing relays 2LG and 4RG control the leaving signals for the single track block, these signals also constituting the head block or entering signalsfor the double track blocks at the opposite ends of the single track stretch shown.

To transmit a control code for clearing signal 2LA or 2LB, lever ZSG is moved to its left-hand position and the starting button ISTB is operated, completing a circuit from terminal B at the lefthand contact e of lever ZSG over contacts e of button IS'IB and relay ZRM through relay 2LG to terminal C at contact e of the track indication relay ITK. Upon the release of the starting button, relay 2LG is held energized over a stick circuit including its own front contact a having one connection to terminal B at back contact e of button ISTB and another at the left-hand contact e of lever 2SG. Contact b of relay ZLGopens the pick-up circuit for relay ZRM. In the control code transmitted when relay 2LG is energized, channel 5 is connected to terminal B over contact 0 of relay ZLG to energize relay [P5, Fig. 2A, so that when relay lD is operated relay ZLHS is energized reverse to clear signal ZLA or ZLB. Relay ZLG is arranged to be released automatically by the track indication relay ITK when a train accepts signal ZLA or ZLB and enters the first track section of its route, and may also be released manually by restoring lever 2SG to its normal position and operating button ISTB which operations also cause the transmission of a control code to restore relay ZLHS to normal, thereby restoring the operated signal ZLA or ZLB to its stop position.

Relay 4RG is similarly controlled by' button 3STB, in accordance with the position of lever 4 ASG and when relay 4RG is energized, its contact b opens the pick-up circuit for relay 41M, while its contact 0 connects terminal B to channel I to to pick up relay 3F! to enable relay 3D to operate relay IRHS to reverse to clear signal 4RA or 4R3.

The circuits for the relays ZLG and ERG above described correspond generally to those for similarly designated relays disclosed in an application for Letters Patent of the United States, Serial No. 648,716, filed February 19, 1946, by James I. Grammer, for Centralized Traffic Control Systems.

Each signal control relay such as relay 2RHS or ZLHS is arranged to be restored to normal upon the release of the track relay, such as relay.

ITR, when a train enters the first track section in advance of the signal, and is then governed control relayis prevented from responding to a signal clearing code after the detector section has been entered by a train, until an indication of its occupancy has been transmitted to the oflice in accordance with an arrangement disclosed in an application for Letters Patent of the United States, Serial No. 649,598, filed February 23, 1946, by Arthur L. Jerome, Lloyd V. Lewis and Frank T. Pascoe, for Centralized Trafiic Control Systems.

The circuits for the master directional relay LP as disclosed herein differ from those of my prior application and are arran ed like those disclosed in an application for Letters Patent of the United States, Serial No. 640,753, filed January 12, 1946, by Lloyd V. Lewis, for Railway Traffic Controlling Apparatus, which issued as Patent No. 2,484,716 on October 11, 1949, in that they include contacts (1 of the starting buttons ISTB and BSTB, as well as contacts 19 and c of a normally deenergized direction locking relay LPS. When the single track block is unoccupied, the

ack indication relays ITK and STK which indicate the condition of the switch sections and the block indication relays ZRBK and 4LBK which indicate the condition of the intervening single track stretch are all released, so that the lamps ITKL, BKE and ETKE in the track diagram controlled by these relays are all dark, while the direction indicator lamp LFE or is lighted to indicate the position of relay LP. If the signal clearing relays 2RM and ELM and the switch lock control relay ZWLM are released and lever ASG is in its normal or right-hand position, relay LES may be energized by operating lever ZSG to the right when lamp LFE is lighted to indicate that the opposing traflic direction is established, in which case the closing of the levelcontact b completes a circuit from terminal 33 over back contacts 19 of relays ZRBK, ALBK, ITK, BTK, 2RM and dLM, right-hand contact b of lever 28G, contact a of lever 4SG, left-hand contact I) of relay LP, back contact a and winding of relay LPS to terminal C at back contact 6 of relay Z WLP. The circuits for the two directions are similar, and when lamp is lighted, relay LPS may be energized by operating lever ASG to the left under corresponding conditions to complete a branch of the circuit just traced which includes the normal or left-hand contact a of lever ZSG, the lefthand contact b of lever 48G and the right-hand contact b of relay LP. When relay LPS picks up, it becomes disconnected from its pick-up circuit by the operation of its contact a, and is held energized over a stick circuit having multiple connections to terminal B at back contacts 0 of the starting relays O lST and 033T, so that relay LPS is held energized until control codes have been initiated, or stored for transmission, to the stations at both ends of the block.

If lever ZSG is operated to the right while lamp R-FE is lighted, or if lever 48G is operated to the left while lamp LF'E is lighted, in order to clear a signal for a train movement in the direction already established, relay LPS remains released and the pressin of the starting button ISTB or 3STB then completes a circuit at its contact a only, whereby the associated starting relay OIST or 033T is energized, but when relay LPS is energized by the operation of a signal lever as described, the pressing of the starting button associated with that signal lever completes three other circuits, in addition. The closing of contact 0 of the operated starting button completes a circuit over contact f of relay LPS to energize a block repeating stick relay BKS over back contact f of relay ZWLP, and the closing of contact at of the operated starting button completes a circuit over contact I) or c of relay LPS for operatin relay LP to the position designating the trafiic directionto be established, while the closing of contact b of the operated button completes a circuit over the reverse contact f of the operated signal lever and contact g or it of relay LPS for energizing the starting relay 0 lST or 038T of the adjoining panel for the station at the opposite end of the block.

The stick circuit for relay LPS is opened as soon as both starting relays are energized, so that relay LPS releases, its pick-up circuit remaining open due to the change in the position of contact b of relay LP. It follows that two codes are initiated to operate the tralfic relays ZRFS and SLFS, respectively, over channel 2, to positions corresponding with that of relay LP.

The energizaticn of relay 015 or 035 during the transmission of the code to the entering end of the block for the direction determined by relay LP causes relay 2RM or 4LM to become energized, as hereinbefore described, locking relays LP and LPS deenergized.

It will be seen that relay LP is free to be operated only when the block is unoccupied, as indicated by the reception of codes which reflect the energized condition of the reversible line circuit system by releasing the block indication relays ZRBK and lLBK. The interruption of the wayside circuits by the trafiic relays ZRFS and 4LFS renders them incapable of indicating the unoccupied block condition while the trafiic direction is being changed, but during this period, it is desirable to permit relay LP to remain operable to either position so that the original traffic direction can be restored if the operator so desires, due to a change in orders or if the reversal cannot be effected, due to a fault. This is accomplished by the provision of the block repeating relay BKS, which is energized along with relay LP as described, and stores the block clear indication, in effect, to maintain relays LP and LPS operable, by closing its front contact in bridging the back contacts b of relays ERBK and ALBK in the circuits for relays LP and LPS until the Wayside circuits are reestablished. When relay BKS picks up, it closes/circuits momentarily over its contacts (1 and e to pick up the block indication relays ZRBK and lLBK locally, placing them in condition to be released by codes indicating the unoccupied block condition, and the closing of the front contacts b of the block indication relays ZRBK and ALBK completes a stick circuit for relay BKS, which relay therefore is held energized until both block indication relays release to indicate the reenergization of the line circuit system. During the period of traffic reversal, the circuits for the direction indication lamps LFE and RFE and for the block indication lamp BKE are all held open at back contact c of relay BKS so that an occupied block indication is not displayed and this period is distinctively indicated on the track diagram by the cancellation of the directional indication.

The operation of the switch lock lever ZWL is also eifective to initiate the transmission of codes to both ends of the block, its contacts a and 7) closing momentarily to energize the starting relays OlST and 038T whenever lever ZWL is rotated from one operating position to another. Contact d of lever BWL controls a repeating re- 11 lay 2WLP by which the circuits governed by relay ZWLP are interlocked by those controlled by the signal levers, that is, the circuit for relay ZWLP includes back contact d of relays ZRM and lLM, and the circuits for relays LPS and BKS include back contacts e and f of relay ZWLP, while the circuits for relays ZRM and QLM include back contact (1 of relay 2WLP. When relay ZWLP becomes energized, its contact c completes a branch of the circuit for relay LP including contact of lever 2WL over which relay LP may be energized in either direction to place it in a position designating the desired direction of traflic movement for a train enterin the block via switch 2W, while contacts a and b of relay 2WLP control the energization of channels 2 and 4 as already described. Since relay BKS is not operated, lamp LFE or RFE is lighted to indicate the position of relay LP and the reversal of the switch lock control relay ZVVLS by one of the codes initiated by the operation of lever ZWL causes an indication code to be transmitted by which relay 2RBK is energized to light lamp BKE and to lock relay LP in its last operated position. Lamp BKE remains lighted, and relay LP is locked deenergized until relay ZWLS is restored to normal by returning lever ZWL to its normal center position.

In prior systems employing the master directional relay LP it has been necessary to include back contacts of the signal indication relays ZRHK and 4LHK in the circuits for relays LP and ZWLP in order to insure that these relays are locked deenergized when an entering head block signal has been cleared for an approaching train. However, it has been found desirable to modify the control of the signal indication relays as hereinafter described, in order to provide additional information of advantage to the operator by arranging them to indicate also the condition of the signal control relays and of the approach locking relays associated with the signals, so that he is enabled to avoid delays resulting from attempts to set up unavailable routes or to reverse trafiic under improper conditions, and When so controlled, the operation of these. relays is such that they would at times unnecessarily restrict the operation of relays LP and 2WLP.

This difficulty is overcome by the provision of the signal clearing relays 2RM, ZLG, lLM and 4RG as herein disclosed and by the control of relays LP and 2WLP by relays 2RM and 4LM as shown herein instead of by relays ZRHK and 4LHK as heretofore.

The block: signaling system Considering now the wayside circuits of Figs. 2A and 213, when Fig. 2B is placed at the right of Fig. 2A, these views show the circuits for a typical single track block extending from the head block signal 2RA or 2RB to the opposing head block signal cLA or 4LB, which as shown is divided into three block sections and is provided with the intermediate signals 2|, 22, 23

and 24.

12 such as the mechanism 4LAG for signal ALA. Each signal mechanism when energized in a normal or reverse direction conditions its signal to indicate proceed or caution, and when deenergized,. to indicate stop. The intermediate signals 2!, 22, 23 and 24 are assumed to be of the color light type, having lamps, not shown, for

7 indicating proceed, caution or stop. The lamp circuits for the intermediate signals as well as the mechanisms G for the head block signals are governed by polarized relays, each identified by the reference character HD prefixed by the designation of the corresponding signal. The signal relays HD for the signals for the single track block are all controlled over the reversible line circuit system, which as shown, comprises three cascade connected line circuits corresponding to the three block sections, the line circuitfor each section including front contact of the track relays TR for the adjacent track sections. Each such signal relay HD is arranged to be energized in series with an ap proach relay AR which governs the lighting of of the next signal in advance in a well-known manner, by means not shown. 7

The signal relays lRHD and 2LHD, which govern the main line head block signals (lRA and 2LA, are normally energized over separate line circuits including the line wires 49, M, 42 and 43 and front contacts of the track relay BTR for the main track section. Signals 2LB and 4R3, for governing traflic movements at slow speed into the side track are governed in accordance with traffic conditions by the detector section track relays 3TB, and ITR, respectively, in a manner hereinafter explained. Relays ARHD and ZLHD are also adapted to serve as approach lighting relays for signals 4LA and ZRA, while signals ALB and ZRB are lighted continuously, in the absence of track circuits in the passing track.

Each signal relay for an intermediate signal, such as relay 2|HD, when energized supplies current of normal polarity to the line circuit for the corresponding relay, such as relay 23HD, for the next signal in the rear, and has associated therewith the usual directional stick relay, such as relay 2|S, which becomes energized when a train passes the corresponding signal at proceed or caution. Each directional stick relay when energized closes its front contacts to supply current of reverse polarity to the line circuit for the next section in the rear, and is held energized only until the associated signal relay HD is again energized; At the ends of the block, the polarity of the current supplied to the line circuit system is controlled by a pole changer relay, such as relay 2LAPC or 4RAPC, controlled by the leaving signal 2LA or ABA, and the line circuit also includes a front contact of an approach locking relay 2RAS or ALAS, which is controlled by the stop indication relay ZRGP or 4LGP for the adjacent entering signals as well as b their control relay ZRHS or 2LHS and by suitable time looking apparatus, as hereinafter described, by means of which the clearing of the opposing signals is prevented except when traffic conditions are proper.

As shown, the contacts a and b of the trafiic relays ZRFS and 4LFS occupy their left-hand positions and the sections of the reversible line circuit system are thereby energized in cascade at their left-hand ends as required for traflic movements from right-to-left. More particularly, the left-hand contacts a and b of relay ZRFS connect terminals B and C of the local 13 source of current at station No. 1 over back contacts a and b of relay Z LAPC' and front contact (1 of relay ZRAS to the left-hand section of the line circuit system, whereby current is supplied over the front contacts a and b of the track relays ITR and 2TR, the line wires 28 and 29 extending to the location of signals 2| and 22, and over front contacts a and b of the track relay ZITR. and back contacts a and b of relays 22S and 221-113, to energize the signal relay ZIHD in series with the approach relay ZLAR. Relay 2 IHD is energized in the reverse direction to condition signal 2| to indicate caution, when signal 2LA indicates stop or caution, while relay 2IHD is energized in the normal direction to condition signal 2| to indicate proceed, when signal 211A indicates proceed, in which case the closing of front contact G of mechanism ZLAG causes relay Z LAPC to assume its energized position. The closing of the front contacts a and b of relay ZlHD connects terminal B of the local source of current at the location of signals 2| and 22 to the intermediate section of the line circuit system extending to the location of signals 23 and 24, the connection to terminal B including a back contact (7. of relay 22HD, the winding of relay Z IAR and front contact (1 of relay ZITR, whereby current is supplied over front contacts a and b of relay Zll-ID, back, contacts a and b of relay ZIS, front contacts a and b of the track relay 22TH, line wires 30 and 3!, front contacts a, b, c and d of a normally energized indication relay ZNWP for the hand throw switch 2W, line wires 32 and 33, front contacts a and b of the track relay 23TH, back contacts a and b of relays 24S and ZQHD to relay 23I-ID. The signal relay 23281) is thereby energized in the normal direction, in series with the approach relay ZlAR, to condition signal 23 to indicate proceed. The closing of front contacts a and b of relay 23I-ID completes a generally similar circuit from terminals B and C of the source at the location of signals 23 and 24, whereby current is supplied over front contacts of the track relays 24TH, iTR and 3TH and the line wires 34 and 35 for the third section of the block, to energize the signal relay lLHD in the normal direction, over the left-hand contacts a and b of the traffic relay lLFS, in series with the approach relay 23AR.

The signal circuits are governed in accordance with the position and locked condition of the track switches WI and 3W by the usual switch repeating relays, such as the relays lNWP and 3NWP which are energized only when their respective switches are locked normal, and relays IRWP and 3RWP which are energized only when the switches are locked reverse.

When the signal control relay 4LHS is operated to reverse by code, with relays 3TB, 3NWP and lLHTD energized, or with relays 3TB and 3RWP energized, a block repeating relay 4BPR. at station No, 2 becomes energized, its circuit extending from terminal B at the normal contact b of relay iRHS over the reverse contact I) of relay ALI-IS, front contact b of relay 4LI-l3) or front contact g of relay IRWP, back contact a of relay ERWP or SNWP, front contact a of relay BNWP or SRWP and front contact at of a repeating relay ETP of the track relay 3TB through relay 14 relay 4BPR is energized thereby, as will be clear from the drawing. The closing of back contact 0 of relay 4LAS completes a circuit for mechanism 4LAG or 4LBG depending upon whether switch 3W is normal or reverse, to clear signal 41A or 4LB.

The circuits for mechanisms 4LAG and 4LBG extend from terminal B at the reverse contact a of relay 4LHS over front contact a of relay 4BPR, contacts 0 of relays 4RAS, 3TER and AILAS, the neutral contact 0 and the pole changer contacts e and f of relay 4LHD, over contacts 0 of relays 3NWP and BRWP through mechanism 4LAG or GLBG to terminal C at contact 0 of relay 4LHS.

It will be seen that the block repeating relay prevents the release of the approach locking re lay 4LAS in response to the reversal of the corresponding signal control relay 4LHS unless a route is available so as to allow the signal to be cleared. If a route is no; available, the operator may restore the signal control relay to normal and then establish a diiferent route without being penalized by a delay due to the time looking which would otherwise have been rendered effective by the release of relay iLAS.

Assuming now that the wayside circuits have been restored to their normal condition for traffic movements from right to left, as shown, and that the operator then transmits a code to station No. l to operate relay ZRHS to reverse, to clear signal ZRA or 2R3. This code will also cause the traffic relay ZRFS to close its righthand contacts, and a second code will be transmitted to station No. 2, causing relay 4LFS to close its right-hand contacts, as already explained. Due to the reversal of relay ERFS, relays ZLAR and illHD, 2 EAR and 23HD, and ZSAR and 4LHD all release, holding signals 2|, 23, 4LA and 4L3 at stop. Due to the reversal of relay 4LFS, terminals B and C of the source at station No. 2 are connected to the line circuit system at its right-hand end. The circuits for the two directions are similar, and it will therefore be evident without further descriptionthat relays Z IHD. 22HD and ZRHD will become energized in cascade, in series with the approach relays 2RAR, MAR. and 22AR, respectively. Signals 24 and 22 will then be conditioned to indicate caution and proceed, respectively, and the block repeating relay ZBPR- will become energized over circuits similar to those traced for relay 4BPR to release the approach locking relay ZRAS and thereby complete a circuit for mechanism 2RAG or ZRBG, depending upon the position of switch IW, to cause signal ZRA or ZRB to clear.

It will be understood that as a train governed by any of the head block signals, signal for example, proceeds through the block, a directional stick relay 2535 becomes energized in response to the release of the track relay 23TR, during the release period of relay 23HD, and when the block section in the rear of signal 23 is vacated, front contacts a and b of relay 23S connect terminals B and C to the line circuit system to energize relay iLHD in the reverse direction whereby signal lLA or 4L3 may be conditioned to indicate caution. Similarly, relay 2IS is energized upon the release of relay 21TH, during the release period of relay ZlHD, whereby relay 23 may be conditioned to indicate caution to govern a following train, or if relay ZNWP is released, to permit relay 2WAR to be energized as required to permit a following train 15 to enter the block over switch 2W reversed, as hereinafter described.

Placing Fig. 2A at the right of Fig. 2B, itwill be seen that relay ZLHD is normally energized with its polar contacts reversed over the circuit extending to terminals B and C at front contacts 6 and f of relay ARAS and including contacts a and b of the track repeating relay STP, the pole changer contacts of relay 4LAPC, line wires 49 and 4! and front contacts of the track relay BTR for the main track section. Relay 4LAPC is controlled by mechanism :iLAG and is energized to operate the polar contacts of relay ZLHD to their normal position when signal ALA indicates caution or proceed.

When the signal control relay 2LHS is operated to reverse by code, with relays ITP, ZLHD and iNWP energized, the block repeating relay ZBPR at station No. 1 becomes energized over a circuit generally similar to that for relay 4BPR already described, and releases the approach locking relay ZLAS. When switch IW is normal, the closing of back contact of relay ZLAS completes a circuit for mechanism ZLAG, which extends from terminal B at the reverse contact a of relay 2LI-IS over front contact I) of relay ZBPR, contacts c of relays ZRAS, 2TER and 2LAS, contacts 0, e and j of relay ZLHD, contact b of relay INWP through mechanism ZLAG to terminal C at contact 0 of relay ZLHS,

whereby mechanism ZLAG is energized to cause signal 2LA to indicate caution or proceed, depending on whether the polar contacts e and f of relay ZLHD occupy their reverse or normal position, respectively.

When switch 3W is reversed, the contacts of relays lRAS and 3TP in the circuit for relay 2LHD are bridged by contacts e and of relay 3RWP, in which case relay ZLHD may be energized to cause signal ZLA to indicate caution, for a movement up to signal iLA, at stop, even though signal 4R3 or ALB has been cleared for a movement over switch 3W reversed.

When switch IW is reversed, relay ZBPR may be energized by reverseing the signal control relay ZLHS regardless of the condition of relay 2LI-ID, over the circuit extending from terminal B at the normal contact b of relay 2RI-IS, reverse contact b of relay ZLHS, front contact g of relay ZRWP, back contact a of relay INWP, front contact a of relay lRWP, contact (1 of the track repeating relay lTP through relay ZBPR to terminal C. Relay 2BPR when energized releases relay- 2LAS, completing a circuit 7 in this instance from terminal B at the reverse contact a. of relay 2LHS over front contact b of relay ZBPR, contacts a of relays ZRAS, ITER and 2LAS, contact b of relay IRWP through mechanism ZLBG to terminal C at contact 0 of relay ZLHS, whereby mechanism ERBG is energized to cause signal ZLB to indicate caution for a slow speed movement into the passing track.

RelayARI-ID, in Fig. 2B, is also normally'energized with its polar contacts reversed, its circuit extending over line wires 42 and 43, to terminals B and C at front contacts of relays ZLAS or of relay IRWP, and when relay SN'WP is energized the reversal of the signal control relay 4RHS causes relay 4BPR to become energized to release relay 4RAS and to cause signal 4RA to indicate caution or proceed by the operation of circuits similar to those for signal 2LA already described. Likewise, when switch 3W is reversed, relay SRWP is energized and the re- Outlying track switch control The hand throw switch 2W, Fig 2B, is normally locked in its normal position as required for main track movements by the magnet ZWLM of an electric lock having a locking segment 25 mounted on a shaft carrying the contacts 41 and 49, the movement of which is limited by a locking dog on the magnet armature. Signals 22 and 23 which govern train movements over switch 2W are prevented from clearing except when the switch is locked normal by including contacts of the switch indication relay 2NWP in the line circuit as already described. Relay ZNWP is normally energized over a circuit which includes a contact N controlled by switch 2W which is closed only when the switch is locked normal, and also includes contact 39 which is closed only when the hand throw lever 8 is locked normal by the lock magnet 2WLM. Segment 25, and contacts 4'! and 4d are also held normally in the position shown by the bail 50 of a padlock, which may be removed by the crew of a train after obtaining authority from the operator to unlock the switch. Segment 25 may then be moved a short distance to open the circuit including contact 49, releasing relay ZNWP, and to close contacts 46-41 in the circuit for magnet 2WLM.

For a train movement from the main track to the side track, magnet ZWLM will then become energized, provided the train has occupied the track section in approach to the switch, for a time sufficient to complete the operation of a time element relay TE controlled over back contacts e and ,f of the track relay 22TH, and the line wires 36 and 31.

For a train movement out of the side track,

the central office operator will have cooperated by moving his switch lever ZWL to the left or right, according to the direction the train is to proceed after it enters the block, thereby initiating two control codes, one of which operates relay ZWLS to reverse and also operates relay ZRFS to the left or right to correspond with the position of lever ZWL, the other operating relay 4LFS to the right, so that terminals B and C become connected to the line circuit system at both ends, in lieu of at one end only. If the block is unoccupied, current is supplied over the line circuit system from both ends to energize the line relays ZWAR and ZEAR at the switch location, provided contact 49 has been opened to release relay ZNWP, and magnet 2WLM may then be energized over contacts i64'l. This permits segment 25 to be moved to its full reverse position, in which lever B is unlocked to permit switch 2W to be operated to reverse.

In the foregoing, it has been assumed that the :block is unoccupied and that the system is in its normal condition as shown, in which case the master directional relay LP is free to respond to the switch lever operation so that either direction of traffic movement may be established. Switch 2W may also be unlocked while the block is occupied, provided the train therein has passed the switch location. In this case relay LP is held deenergized, retaining the established traffic'direction, but one or the other of the two codes transmitted in response to the reversal of lever ZWL will be efiective to energize the line circuit system at the station in the rear of the train occupying the block, and when this train The code indication system Each indication code is initiated by release of a normally energized starting relay such as relay lST at station No. 1, which as shown by the circuits, occurs either in response to a change in the position of one or more or the indicating relays, or due to the momentary opening of contact 7 of the delivery relay lD, when a control code is received. In each code initiated by relay lST, a selector relay 5 at the station is energized along with a delivery relay Oil) in the corresponding ofiice panel, in response to the station code call, to extend the indication chan nels ele from the selected station to the corresponding ofllce panel. At station No. 1, only channels id, 13, i l and it are shown herein, over which the indication stick relays lTK, tTK, ZLHK, 2325K. and ERHK are energized in response to the closin of back contacts of the corresponding indicating relays ETKS, ETR, ELGP, ZRBP and 2R6? at station No. 1. ihe release of the similar starting relay at station No. initiates a code in which a selector relay 3S and a delivery relay 03D are energized to control the indication stick relays ll-BK, QLHK and over channels i i, l2, l3 and i5, and back contacts of relays 3TKS, iLBP, fiiLGP and lRGP, respectively.

Relays ITK and 3TB: are the usual track. indication relays which control the lamps ITKE. and BTKE in the OS sections of the track diagram, and which also usually control pen magnets in a train graph as described in Patent No. 2,229,249. To prevent the loss of the indication of the arrival of a train at a station in the event the transmission of indications is delayed and the train vacates the controlling track section before an indication of its occupancy is transmitted, a storage relay such as relay lTKS is provided.

When a train enters the detector track section IT and releasesthe track relay iTR, the opening of contact (t of relay ITR releases relay lTKS, which relay by momentarily opening its contact releases the starting relay 1ST to store the indication code for transmission as soon as the code line becomes available. Relay MS? is energized during the transmission of this code as described in Patent No. 2,229,249, and relay HST is reenergized during the eighth step, that is, during the step immediately preceding the series of steps during which the indication channels 9-li'r are established. he contacts of relays MSP and EST in the picleup circuit for relay STKS serve to hold this circuit open until the code is fully transmitted, thereby insuring the energization of the track indication relay ITK over channel is, even though the transmission of this code occurs after section ET is vacated and relay lTR is rcenergized.

Relays ZRBK and lLBlji are block indication relays controlled from stations Nos. 1 and 2 over channels I l and 52. Contacts 0 of these relays jointly control the block indication lamp Bil IE in the track diagram, which lamp is lighted to indicate the presence of a train in the block when All either relay ZRBK or dLEK is energized by a received code, but not when these relays are energized locally by relay BKS, as already explained.

When the right-to-left direction is set up, re lay :iLBP, the release of which initiates the transmission of an indication code for energizing relay iLBK, is held energized, as shown in Fig. 213, over the neutral contact a and the normal polar contact 11 of the signal relay lLHD, only when the intermediate and right-hand block sections are both unoccupied, while relay 'ZRBP, the release of which initiates the transmission of an indication code for energizing relay ZRBK, is held energized, as shown, over contact a of the approach relay '2LAR, only when the left-hand block section is unoccupied.

When the l ft-to-right direction is established, relay ZRBP is energized over contacts a and d of relay ERHD provided the lefthand and intermediate block sections are unoccupied, and relay lLBP is energized over contact a of relay 4RAR, provided the right-hand block section is unoccupied.

A modification of this arrangement is required when the block contains more or less than three sections, as is obvious. Thus when the block contains more than three sections, line wire control may be employed to bridge the additional sections as disclosed in Fig. 2c of Letters Patent of the United States No. 2,344,333, issued March i l, 19%, to James J. Van Horn, for Railway TraffLC Controlling Apparatus. When the block contains less than three sections, it is of advantage to transmit the block indications from one end of the block only, to reduce the number of indication codes transmitted, by omitting the circuits including contacts a of the approach relays, as disclosed in a pending application for Letters Patent of the United States, Serial No. 567,188, filed December 8, 1944, by Frank T. Pascoe and Arthur L. Jerome, for Railway Traffic Controlling Apparatus, which issued as Patent No. 2,411,387, on November 19, 1946. In this arrangement, the relay ZRBK or iLBK for the exit end of the block is energized regardless of trafiic conditions because the signal relay which controls it is released, requiring a change in the connection of the front contacts 12 and c of these relays from parallel to series, and of their back contacts 1) from series to parallel, as illustrated in Figs. 2 and 3 of the application referred to, in order to enable the circuits controlled by these contacts to function in the normal manner, as hereinbefore described.

Lamp BKE. is also lighted upon the reception of the return indication code which follows the switch lock control codes initiated by the reversal of the switch lock lever 2WL, as already mentioned. One of these control codes reverses relay EWLS and the other reverses relay ALFS. The opening of contact 0 of relay EWLS releases relay ZRBP, thereby initiating an indication code by which relay ZRBK is energized, which sufiices to light lamp BKE when the contacts 0 of relays ZRBK and lLBK are connected in parallel as shown, as is obvious. In the case of the short block mentioned, where these contacts are connected in series, lamp BKE will also be lighted in response to the reversal of lever ZWL, due to the energization of both block indication relays.

The signal indication relays QRHK and. ZLHK control a red lamp ZNE and green lamps 2LE and 213.111 associated with lever 28G, as shown in Fig, 1, and the relays @RHK and 4LHK control the lamps lLEl, 4NE and lRE associated with 19' lever 48G, by similar circuits, not shown. The signal indication relays are controlled over channels l3 and I5, and by reference to Fig. 2A it will be seen that normally, the signals at s-tation No. 1 are at stop and their indication relays 2LGP and 2RGP and the approach locking relays ZLAS and ZRAS are all energized, in which case channels I3 and I5 are not energized and relays ZLHK and ZRHK assume their released position in response to the operation of relay OID, thereby completing a circuit over their back contacts :2 to light the red lamp ZNE If now relay 2RI-IS or ZLHS is reversed by a control code, energizing relay ZBPR and thereby releasing relay 2RAS or ZLAS, and if due to a fault, the signal fails to clear so that relays ZRGP and ZLGP remain energized, terminal B at back contact g of relay ZLAS or QRAS is connected over front contacts a of relays ZRG-P and ZLGP to channels l3 and l5, and relay IST is released by the momentary opening of contact h of'relay ZRAS or ZLAS- to initiate an indication code whereby relays 'ZRHK and ZLHK are both energized. Lamp 2NE is thereby connected over front contacts 0 of relays ZLHS and ZRHS to a source of coded or interrupted current identified by the reference character CB, and is so caused to display a flashing indication indicating the approach locked condition. If one of the signals governed by the operated control relay 2RHS or ZLHS assumes its energized position, the corresponding indication relay 2RGP or 2LGP releases and. by opening its contact 0 initiates a second code. If signal 2RA o r 2RB clears, relay ZRGP releases and its contact a disconnects terminal B from channel l3 but not from channel l5, and in response to the code, relay ZLHK is released and relay 2RHK is held energized, to extinguish lamp ZNE and light lamp ZRE- over front contact (1 of relay ZRHK and back contact e of relay ZLHK. Similarly, if signal ZLA or ZLB clears, relay 2LGP releases to disconnect terminal B from channel but not from channel I3, so that relay 2LHK is energized and relay ZRHK released to light lamp 2LE.

When a cleared signal is restored to stop, reenergizing relay ZRGP' or ZLGP, the approach locked indication code by which both relays 2RHK and ZLI-lK are energized will be transmitted in lieu of the stop indication code by which both these relays are released, if either I relay ZRAS or 2LAS remains released, as will be readily apparent.

Operation I shall first assume that the system is in its normal condition as shown, with lamp LFE lighted to indicate that the right-to-left traffic direction is set up but with signals ALA and lLB at stop, and shall trace the operations for clearing signals ERA and ARA for a train movement from left-to-right.

The operator moves lever ZSG to the right, which completes a circuit from terminal B at back contact I) of relay ERBK over back contacts b of relays dLBK, ITK, STK, ZRM and LiLM; the right-hand contact I) of signal lever 28G, the normal or right-hand contact a of lever 48G, left-hand contact b of relay LP, back contact a and winding of relay LPS to terminal C at back contact e of relay ZWLP. Relay LPS picks up and completes a stick circuit at its own front contact a extending to terminal B at back contacts c of relays O IST and 038T.

The operator then presses button ISTB, en-

ergizing relay OIST over the button contact d, and energizing relay 035T over the circuit from terminal B at the right-hand contact 1 of lever 2SG, contact b of button ESTB, contact h of relay LPS, through relay 038T to terminal C, also energizing relay BKS over the circuit extending from terminal B at contact 0 of button ISTB, contact I of relay LPS through relay BKS to terminal C at back contact I of relay ZWLP, and energizing the relay LP over the circuit including contacts I) of the indication and signal clearing relays ZRBK, lLBK, E'IK, 3TK, ZRM and lLM and of lever ZSG, contact a of lever @SG, contact d of button lSTB, and contact 7) of relay LPS through the upper Winding of relay LP to terminal C, whereby rela LP is operated to close its right-hand contacts.

The starting relays OlST and 0331 are held energized over back contacts 2' of the corresponding selector relays 013 and 03S and open the stick circuit for relay LPS, which relay therefore releases after a brief period but without reestablishing its pick-up circuit, due to the opening of left-hand contact I) of relay LP. Before relay LPS releases, circuits are completed momentarily over contacts d and e of relays BKS and LPS to pick up the block indication relays 2RBK and ALBK, which relays thus assume positions corresponding to the occupied block condition and are held energized over their stick circuits including their own front contacts a and the back contacts J and d of the delivery relays O! D and 03D, respectively, and by closing their front contacts I), complete a stick circuit for relay BKS including back contacts (1 of relays ITK and 3TK and front contact a of relay BKS for holding relay BKS energized. The opening of back contact 0 of relay BKS extinguishes lamp LFE and maintains lamps RF'E and BKE dark, while the closing of front contact b of relay BKS prepares a circuit for the lower winding of relay LP which is open at contact c of relay LPS, while the circuit for the upper winding of relay LP as traced above is now open at contact b of relay LPS.

The closing of contacts 0 of relays OiST and OBST initiates the transmission of control codes to the corresponding stations Nos. 1 and 2 at the opposite ends of the block, as described in Patent No. 2,229,249. In the code initiated by relay OIST, relays OiS and ID are operated, and as soon as relay 01S picks up, relay ZRM is energized over the circuit from terminal B at front contact h of relay OM, contacts 11 of relays EWLP, LP and OlS, contact 0 of lever 25G, back contact b of relay 2LG through relay ZRM to terminal C at back contact e of relay iTK. Relay ZRM picks up and completes a stick circuit extending to terminal B at back contact I) of relay 2- lZ and opens its back contacts I), d and e to lock relays LP and LPS, ZWLP and ZLG deenergized. Relays OlS connects terminal B to channel 7 only, in this instance, and since the connection fromcontact c of rela LP to 'chan nel 2 over contact e of relay 058 is now open, relay IFZ, Fig. 2A, is not operated and relay ZRFS is operated to close its right-hand contacts a and b, by relay ID. Channel 4 is open, so that relay 2WLS is operated to the left, but channel I is energized over contact 9 of relay OIS, contact d of lever 23G, contacts e of relays ZRM and 24Z, and contact 0 of relay LP, so that relay IFT is energized and relay ZRHS is operated to the right. In the code initiated by relay 038T, relays 03S and 3D are operated, en-

21 ergizing channel 2 only, over contact a of relay LP, back contact is of relay LPS, and contact 6 of relay 038, to operate relays 4LFS to the right.

It may be that the operator will have also operated lever 48G to th right, with the intention of clearing signal dRA or 4R3, but without operating button 3STB because at the time he is uncertain which of these signals he wishes to clear. The reversal of lever 486% is without effect upon the code transmitted to station No. 2 b the operation of button IS'IB as above described, because relay 4RG has not been energized. The operator may however render this code eilective to clear signal dRA or 4RB by pressing button 3STB before it is transmitted, to pick up relay 4RG over contacts e of lever 48G and of button ESTB, in which case channel I will be energized over contact 0 of relay 4RG and relay 4RHS will be operated to reverse by the code by which relay lRFS is operated.

Relays ZRFS and ALFS in their right-hand positions reverse the direction of energization of the line circuit system as hereinbefore described. Relay 4LBP is picked up by relay 4RAR,

and relay ZRBP by relay ZRHD, and since the right-hand contacts of relay ZR-HS are closed, relay ZBPR is energized by relay ZRHD when the energization of the line circuit system is com pleted, releasing relay ERAS and thereby energizing mechanism ZRAG to clear signal ZRA, the energization of mechanism ZRAG causing relay ZRGP to release.

These operations result in the initiation of one or more indication codes from each station, 3,

whereby relays ZRBK and 4LBK are released, thereby releasing relay BKS and lighting lamp RFE to indicate the trafiic direction established, and relay ZRHK becomes energized, lighting lamp ZRE to indicate the clearing of signal ZRA or ZRB.

Usually these codes will all be transmitted be fore the train governed by signal ZRA enters the block, but if the code system controls a large number of stations and the traffic is heavy, it

may happen that the train will pass signal ZRA. at clear and enter the block before the system has an opportunity to transmit the indication code by which relay ZRHK is energized and relay ZRBK released. ceived from station No. 1, following the transmission of the control codes for reversing the trafiic direction, will be the OS code, energizing relay ITK, even though the train has vacated the detector section before this code is transmitted, due to its storage by relay ITKS. The opening of contact e of relay ITK releases relay ZRM, but the opening of contact b of relay ITK now holds relays LP and LPS deenergized, and the opening of contact (1 of relay ITK releases relay BKS, rendering relay ZRBK effective, provided it is maintained energized by this code, to light lamp BKE to indicate the occupied block indication. Due to the release of relay BKS by relay ITK, relays ZRBK and ILBK are rendered effective to maintain relays LP and LPS deenergized, after relay ITK is released, by a code transmitted from station No. 1 to indicate that the train has vacated the detector section. Lamp RFE also becomes lighted to indicate the established direction of traflic as in the preceding example.

It Will be seen that lamp BKE indicates whether or not the block is occupied only when lamp RF'E or LFE is lighted to indicate that the corresponding direction of trafiic is established,

In this case, the first code re- 2.2 and that while the traffic direction is being established all three lamps are dark.

The operator may wish to repeat the control operations above described, in the event the transmision of the code indicating the clearing of signal 2RA or ZRB is delayed, and will reoperate the starting button ISTB. This will result in the transmission of a code to station No. i only, since relay LPS will not be operated. This code being a repetition of that previously transmitted, will merely maintain relays ZRFS and ZRHS reversed, provided it is received before the train enters the detector section IT. When the train enters section IT, relay I'IR is released and relay ZRHS- is operated to normal by the momentary energization of its lower winding over contacts 1 of relays ITR. and ITKS. Relay ITR. releases relay ITKS, as already explained, and contact e of relay ITKS =disconnects the upper winding of relay ZRHS from the pole changer contacts a and b of relay FF? and connects it to back contact 0 of that relay. Relay ZRHS is thus rendered non-responsive to a signal clearing code received While relay ITKS is released and so remains in its normal position if this code is repeated after the train enters the detector section but before the OS indication has been transmitted by which the signal clearing relay ZRM is released.

Assuming that the train has vacated section I T when the track occupied code is transmitted, relay iST becomes reenergized, and relay ITKS picks up, whereupon relay IST releases again to store a track unoccupied code for transmission. Relay ilRI-IS is now in condition to respond to the energization of channel I, but since the indication relay HTK is energized, relay ERM is held released, preventing the energization of channel 1 in a code transmitted to station No. 1. It follows that signal ZRA or ZRB may be cleared for a following train only by operating button iSTB after an indication is received that the first train has vacated section IT.

It may be that the operator after having initiated the reversal of traffic as above described will wish to restore the original trafiic direction, due to a change in orders or in case it is found that the reverse direction cannot be set up due to a fault. It has already been pointed out that the block indication relays ZRBK and iLBK are incapable of indicating block conditions at this time and are held energized locally, relay BKS having been energized to prepare circuits for relays LPS and LP, but these circuits are now held open at back contact b of relay ZRM. The operator will therefore take steps leading to the release of relay ZRM, in order to unlock the traflic direction apparatus, by restoring lever ZSG to its normal position and pressing button ISTB, to cause the transmission of a signal stop code for restoring relay ZRHS to normal. On the eighth step of this code, relay 2-4Z is picked up over back contact a of relay MBP, contact 0 of relay OIS, contact 9 of lever 28G, and contact e of relay ZRM, completing a stick circuit at its own front contact a, and extend ing the stick circuit for relay ZRM over front contact b of relay 2- iZ to terminal B at back contact 71. of relay OID.

Channel I is open at contact d of lever ZSG and at contact e of relay 2-42, and when the delivery relay ID is operated by this code, relay ZRHS is operated to normal, and relay lST is 75 released to initiate a return indication code.

Assuming first that the traffic reversal had not been completed and that the approach locking relays ERAS and ZLAS are both energized so that channels I3 and i5 are open. When the delivery relay OED is operated by this indication code, relays ZLHK and QRHK remain released to maintain lamp ZNE lighted and since channel i5 is open, relay ZRM is released by the operation of contact h of relay OID, and relay 24Z is then released by the opening of contact e of relay ZRM. The fact that relay ZRAS is found to be in its energized condition manifests that signal ZRA or ZRB has not been cleared.

Assuming now that the operations involved in reversing traflic had progressed further before this signal stop code is transmitted and that relay ZRAS has been released, the operation of relay ZRHS to normal by the code will restore signal ZRA or ZRB to stop, if it has been cleared, reenergizing relay 2RGP and completing a circuit over back contact a of relay ZRAS for the time element relay ITER, by means of which relay 2RAS is reenergized after a predetermined time interval. Channels I3 and I5 are both supplied with current over back contact g of relay ZRAS, and when relay OID is operated by the return indication code, relays ZRHK and ZLHK are picked up to cause lamp ZNE to display a flashing indication, to indicate the approachlocked condition, and relay 2RM will remain energized, being connected to terminal B over channel i5 while back contact 71. of relay OID is open. At the end of the time delay period, relay ERAS is picked up by relay ITER and initiates a second indication code to release relays ZRI-IK, ZLHK and to also release relay ZRM to condition relay LPS for operation as in the preceding examples.

In each of the foregoing examples, the unoccupied block indication stored by relay BKS corresponds to the actual conditions, making it proper to reverse traffic as soon as relay ZRM is released, provided relay BKS remains energized. It may be however, due to an extended delay in the transmission of indication codes, that the train will have entered the block and will be approaching one of the intermediate signals at clear, at the time the operator decides to reestablish his control of the trailic direction apparatus by the transmission of a signal stop control code for restoring the signal control relay 2Rl-IS to norclude the stored OS indication by which relay ITK is energized over channel [0, channels i3 and [5 being open. This indication code will release relays ZRM and 2-4Z as in the preceding examples and for the additional reason that contact 6 of relay ITK is opened, but at the same time contact I) of relay ITK opens to hold relay LPS deenergized, and relay BKS is released by the opening of contact d of relay ITK, while relays ZRBK and GLBK remain energized to hold relay LPS deenergized until indications that the entire block is vacated are received. It will be clear therefore, that relay BKS ceases to be effective when relay ZRM is released by an OS code, and that the operator is enabled to regain control of the traffic direction apparatus only when relay 2RM is released by an indication code which indicates that the block has not been entered. One important advantage of this arrangement is that it prevents the operator from inadvertently causing an intermediate signal to be put to stop 24 in front of a train, the presence of which in the block has not been indicated at the oilice.

I shall now trace the operations involved in un10cking switch 2W, assuming that the right-toleft trai'lic direction is set as shown, and also assuming that the crew of a train on the siding at switch 2W has communicated with the operator by telephone, requesting authority to enter the block and to move their train in the opposite direction, that is toward the right.

The operator moves lever ZWL to its right-hand position, leaving the signal levers ZSG and 48G both in their normal positions, as shown. Contacts a and b of lever ZWL close momentarily, energizing the starting relays OIST and 033T to initiate the transmission of control codes to stations at both ends of the block. The

closing of right-hand contact d of lever 2WL completes a circuit from terminal B over back contacts (1 of relays 2RM and ALM to ener- It may be assumed that levers 2SG and 48G will be left in their normal positions, but this is not essential, since channels 5 and 1 will be held open and relay LPS will remain released even though the signal levers are displaced from normal, because the circuits for relays ZRM, 4LM, LPS and BKS are held open by relay ZWLP, and the energization of relays 2LG and ARG requires the combined operation of the signal lever and the associated starting button. The inadvertent reversal of a signal lever therefore has no effect upon the control codes initiated by the reversal of the switch lock lever 2WL.

In the code transmitted to station No. l, channel 2 is not energized, but channel 4 is energized over contact I) of relay ZWLP, and in the code transmitted to station No. 2, channel 2 is energized over contact a of relay ZWLP and also over the right-hand contact 0 of relay LP. Consequently these codes serve to operate each of the relays ZWLS, 2RFS and ALFS to the right, in which case, as will be clear from Figs. 2A and 2B, the line circuit system is supplied with current at both ends.

In Fig. 2A, terminals B and C are now connected to the line circuit for relay 2 [HD over the right-hand contacts a and b of relays ZWLS and ZRFS instead of over the left-hand contacts of relay 2RFS so that relays ZLAR and 2IHD remain energized, likewise relay 23HD, but relay 4LHD is released by relay 4LFS so that signals 2! and 23 remain in condition to indicate caution and proceed, respectively, but the head block signals are all held at stop. The opening of contact 0 of relay ZWLS releases relay ZRBP, initiating an indication code by which relay ZRBK is energized to lock relay LP deenergized and to light lamp BKE. Lamp LFE is extinguished and lamp RFE lighted in response to the operation of relay LP by the switch lever, because relay BKS is not operated.

When the switch lock segment is operated by the train crew to its intermediate position relay ZNWP releases, thereby releasing relay 23HD to condition signal 23 to indicate stop and relay ZWAR becomes energized. The release of relay 23HD allows relay Edi-ID to become energized in series with relay ARAR to condition signal 24 to indicate caution and to supply current to the line circuit section in the rear thereof to energize relay ZEAR. Relays Elf/AR and ZEAR when energized complete a circuit over contacts 46-47 for the lock magnet ZWLM to permit switch 2W to be unlocked.

Segment 25 is then operated to its full reverse position to unlock lever B, and the switch is reversed by the operation of lever 8 to permit the train to enter the main track and to release relays ZSTR and 22TH, which in turn release relays ZEAR, and EWAR. The train crew then locks switch 2W normal, relay ZNWP becoming reenergized.

The operator when advised that the switch is locked normal, may restore lever ZWL to its normal center position. This again closes contacts a and b of lever ZWL momentarily to initiate the transmission of codes to both ends of the block. Relay ZWLP is released by the opening of contact cl of lever 2WL, and it follows that in response to these codes relay ZWLSis operated to the left, relays ERFS and iLFS remaining in their righthand positions. Relays 2LAR and ZIHD release, relay ZRBP remains released and maintains relay 2RBK energized, so that lamp BKE remains lighted, indicating the occupancy of the block. The release of relay ZiHD restores signal 23 to stop. As the train passes signal 24 at caution, relays 24TH, 24HD, 4RAR and ELBP release and the directional stick relay 24S becomes energized, and an indication code is initiated by relay ALBP by which the block indication relay L-BK is energized.

It will be noted that if lever ZSG is moved to the right prior to the restoration of lever ZW'L to normal, the code initiated by the operation of lever ZWL which is transmitted to station No. 1 will be effective to reverse relay ZRHS, but the code transmitted to station No. 2 will be effective to reverse relay QRHS only if button ZSTB is operated while lever 4SG occupies its right-hand position, in order to pick up relay iRG.

Since relay 2 38 has been picked up, it follows that when th train vacates the intermediate block section, relay becomes energized in the reverse direction, energizing relay llRl-ID in the normal direction, thereby energizing relay ZRBP which initiates a code by which relay ZRBK is released, but lamp BKE remains lig ,ted due to the energization of relay lLBK, until the train vacates the block. Signal 22 is conditioned to indicate caution, and if relay QRHS has been reversed, the energization of relay ZRHD causes signal ERA or 2R3 to be conditioned to indicate proceed to permit a following train to enter the block.

Assuming next that with the right-to-left traffic direction set up as shown, that the switch 2W is to be unlocked to permit a train to enter the block and to move in the established direction, toward the left. In this case the operator moves lever 2W1, to the left, energizing relay EWLP and the lower winding of relay LP, holding relay L in its leit-hand position, and initiating codes by which relays ZWLS and lLFS are operated to the right by relay ZWLP, and relay 2RFS is held in its left-hand position by relay LP, energizing the line circuit system at both ends so that switch. 2W may be unlocked, as in preceding ex ample.

Since in this instance the traffic direction is not changed, these operations may be carried out while the block is occupied by a preceding train, provided it has vacated the block section containing switch 2W. Thus if the left-hand section is occupied by a train moving toward the left, the directional stick relay 2|S will be energized in lieu of relay ZlI-ID, to supply current to relay ZWAR in response to the release of relay 2NWP, the operations in other respects being similar to those already described.

Although I have herein shown and described only one form of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. Railway trairic controlling apparatus for governing tratlic movements in a stretch of single track railway equipped with a reversible signaling system having an entering signal at each end controllable by a signal control relay in accordance with traffic conditions in the stretch when the corresponding trafiic direction is established, comprising a directional relay for designating the direction oi traffic movement, a signal lever and a signal clearing relay for each signal all located at a control office, a code type communication systern for transmitting control codes to the signal locations to operate the signal control relays and for transmitting indication codes to the office for indicating traific conditions in the stretch, means for operating said directional relay in response to the reversal of either signal lever to a position designating the corresponding tramc direction provided said signal clearing relays are deenergized and the unoccupied block condition is indicated said code system, means acting when a control code is transmitted with either signal lever reversed for energizing the associated signal clearing relay, means rendering such code effective to operate the correspondin signal control relay to effect the clearing of its signal only if such signal clearing relay is energized, and means for maintaining such signal clearing relay energized until an indication code is received which indicates that the operated signal control relay has been restored to its normal position.

2. Railway traffic controlling apparatus located at a central office for controlling traflic in a stretch of single track railway equipped with an entering signal at each end governed from said oilice by a signal control relay and also governed in accordance with traffic conditions in said stretch, a signal lever and a signal clearin relay controlled thereby for each signal, a two position directional relay for designating the direction of traffic movement in said stretch, a code type com munication system havin a starting relay for each signal lever, a starting button for each signal lever effective when operated to actuate its starting relay to thereby initiate the transmission of a code reflecting the position of the associated signal lever and of its signal clearing relay and also that of said directional relay, to which code the signal clearing relay at the corresponding end of the stretch is responsive, a track indication relay for each end of the stretch arranged to be energized when a train enters the stretch at the correspondin end, a normally deenergized direction locking relay, a circuit for energizing said direction locking relay closed upon the operation of one signal lever or the other to its'signal clearing position including back contacts of both signal clearing relays and of both track indication relays and also including a contact of the directional relay closed only when a reversal of traflic direction is required in order to clear the signal controlled by the operated lever, circuits closed by the operation of the starting button for such lever when the direction locking relay is energized for operating the directional relay to the position designating the corresponding trafiic direction and for then releasing said direction locking relay, a circuit closed upon the initiation of a code by the starting relay which such button controls for energizing the signal clearing relay associated with the operated signal lever, and a circuit for maintaining such signal clearing relay energized only until the track indication relay for the corresponding end of the stretch becomes energized.

3. Railway traffic controlling apparatus located at a central omce for controlling traffic in a stretch of single track railway equipped with an entering signal at each end governed by a signal control relay and also governed in accordance with trafiic conditions in the stretch, a code type communication system connecting said ofiice with stations at the ends of the stretch, said apparatus comprising a two position directional relay, a signal lever and a signal clearing relay for each signal, a starting button for each lever effective when operated to actuate a starting relay associated therewith to initiate the transmission of a code by said communication system reflecting the positions of the associated signal lever and of its signal clearing relay to which the signal control relays at the corresponding end of the stretch are responsive, means controlled by the signals for indicating their condition and that of their control relays, indication relays controlled by traffic conditions for indicating when the stretch is unoccupied, a normally deenergized direction locking relay, a circuit for energizing said direction locking relay closed upon the operation of onesignal lever or the other to its signal clearing position including back contacts of the signal clearing relays and contacts of said indication relays which when closed indicate that the stretch is unoccupied, and also including a contact of the directional relay closed only when a change in the traflic direction indicated by such relay is required in order to clear the signal controlled by the operated lever, circuits closed by the operation of the starting button for the operated lever when the direction locking relay is energized for operating said directional relay to the position required to establish the corresponding direction and for actuating the starting relays associated with both signal levers, a circuit for maintaining said direction locking relay energized after the directional relay is operated only until both starting relays are actuated, a circuit controlled by said directional relay for energizing the signal clearing relay for the operated signal lever in response to the initiation of a code by the associated starting relay, and means for maintaining such signal clearing relay energized only until indications are received which manifest that the signal control relay governed by such code has been restored to its normal position.

4. Direction selecting apparatus for controlling trafiic movements over a stretch of single track railway equipped with a reversible signaling system having an entering signal at each end pro 28 vided with a control relay for governing its operaticn in accordance with traffic conditions in the stretch when the signaling system is set up in the corresponding direction and also having a two position directional relay for designating the direction of traffic movement, a code type communication system for transmitting manually initiated control codes to stations at the ends of the stretch to operate the control relay at the entering end designated by said directional relay and to energize said signaling system at its opposite end as required for the clearing of the entering end signal, and for also transniitting indication codes from said stations to report the condition of said signals and of their control relays, a manually controllable signal clearing relay, circuit means requiring said signal clearing relay to be energized to render a control code transmitted to the station at the entering end of the stretch efiective to operate the control relay thereat to its signal clearing 7 position; means for energizing said signal clearing relay when such code is initiated, and means controlled by said signal clearing relay for preventing a change in the position of said direc tional relay from the time said signal clearing relay becomes energized until the operated signal control relay is returned to normal and the signal governed thereby is returned to its stop position and its return is reported by an indication code transmitted by said code system.

5. Direction selecting apparatus for controlling traffic movements over a stretch of single track railway equipped with a reversible signaling system having an entering signal at each end provided with a control relay for governing its operation in accordance with trafiic conditions in the stretch when the signaling system is set up in the corresponding direction and also having a two position directional relay for designating the direction of trafiic movement, an approach locking relay for each signal which when energized manifests that the signal is at stop and that its control relay is in a normal position, a code type communication system for transmitting manually initiated control codes to stations at the ends of the stretch to operate the control relay at the entering end designated by said directional relay and to energize said signaling system at its opposite end, provided the approach locking relay thereat is energized, to effect the clearing of the entering end signal, and for also transmitting indication codes from said stations to report the condition of said approach locking relays, a manually controllable signal clearing relay, circuit means requiring said signal clearing relay to be energized to render a control code transmitted to the station at the entering end of the stretch effective to operate the control relay thereat to its signal clearing position, means for energizing said signal clearing relay when such code is initiated, and means controlled by said signal clearing relay for preventing a change in the position of said directional relayfrom the time such control code is initiated until the reenergization of the approach locking relay at the entering end is reported by an indication code transmitted by said code system.

6. Direction selecting apparatus for controlling traffic movements over a stretch of single track railway equipped with a reversible signaling system having an entering signal at each end provided with a control relay for governing its operation in accordance with trafiic conditions in the stretch when the signaling system is set up in the corresponding direction and also having a two position directional relay for designating the direction of traflic movement, an approach looking relay for each signal which when energized manifests that the signal is at stop and that its control relay is in a normal position, a code type communication system for transmitting manually initiated control codes to stations at the ends of the stretch to operate the control relay at the entering end designated by said directional relay and to energize said signaling system at its opposite end, provided the approach looking relay thereat is energized, to efiect the clearing of the entering end signal, and for also transmitting indication codes from said stations to report the condition of said approach locking relays, a manually controllable signal clearing relay for each direction, means for energizing the signal clearing relay for the direction designated by said directional relay when the transmission of a code to the station at the entering end for such direction for clearing the signal at such station is initiated, means controlled by such signal clearing relay when energized for rendering such code eiiective to operate the signal control relay at such entering end to its signal clearing position and to prevent a change in the position of said directional relay, and means for maintaining such signal clearing relay energized in the event the stretch is not entered by a train, until the reenergization of the approach locking relay released in response to such code has been effected by the transmission of a second control code for restoring the cleared signal manually to stop, and the reenergization of such relay is reported by an indication code transmitted by said code system.

'7. In combination with a stretch of single track railway having an entering signal at each end governed by traffic conditions in the stretch and by a signal control relay controlled by a signal lever at a central oifice, a code system for transmitting manually initiated control codes to operate said control relays in accordance with the positions of said levers and for transmitting indication codes to operate indication relays at the oilice reflecting the condition of occupancy of the stretch and the condition of the signals and of their control relays, a two position directional relay for designating the direction of traffic movements, a signal clearing relay for each signal, circuits closed in response to the operation of either signal lever when the other signal lever is normal for operating said directional relay to a position designating the direction of traflic governed by the operated lever, said circuits including back contacts of both signal clearing relays and contacts of said indication relays which when closed indicate that the stretch is unoccupied, means rendering a control code governed by the operated lever effective to operate the signal control relay which such code controls to its signal clearing position only if transmitted when the associated signal clearing relay is energized, means controlled by the directional relay in the position designating the corresponding traific direction for energizing such signal clearing relay upon the initiation of such code, means for maintaining such signal clearing relay energized following the transmission of said control code either until an indication code is received indicating that a train governed by the signal cleared in response to such code has entered the stretch, or an indication code is received indicating that the signal has been manually restored to stop by the transmission of a second control code, and means for auto matically restoring said signal control relay to its normal position when said train enters the stretch.

8. In combination with a stretch of single track railway having an entering signal at each "end governed by traffic conditions in the stretch and by a signal control relay controlled by a signal lever at a central office, a code system for transmitting manually initiated control codes to operate said control relays in accordance with the positions of said levers and for transmitting indication codes to operate indication relays at the officeireiiecting the condition of occupancy of the stretch and the condition of the signals and of their control relays, a two position directional relay for designating the direction of traflic movements, a signal clearing relay for each signal, circuits closed in response to the operation of either signal lever when the other signal lever is normal for operating said directional relay to a position designating the direction of traffic governed by the operated lever, said circuits including back contacts of both signal clearing relays and contacts of said indication relays which when closed indicate that the stretch is unoccupied, means rendering a control code governed by the operated lever effective to operate the signal control relay which such code controls to its signal clearing position only if transmitted when the associated signal clearing relay is energized, means controlled by the directional relay in the position designating the corresponding trafiic direction for energizing such signal clearing relay upon the initiation of such code, and means for maintaining such signal clearing relay energized following the transmission of said control code until an indication code is received indicating that either a train governed by said signal has entered the stretch or that the signal cleared in response to said code has been restored to stop and that its control relay occupies its normal position.

In combination with a stretch of single track railway having an entering signal at each end governed by traffic conditions in the stretch and by a signal control relay controlled by a signal lever at a central ofiice, a code system for transmitting manually initiated control codes to operate said control relays in accordance with the positions of said levers and for transmitting indication codes to operate indication relays at the office reflecting the condition of occupancy of the stretch and the condition of the signals and oftheir control relays, a two position directional relay for designating the direction of traffilc movements, a signal clearing relay for each signal, circuits closed in response to the operation of either signal lever when the other signal lever is normal for operating said directional relay to a position designating the direction of trailic gov erned by the operated lever, said circuits including back contacts of both signal clearing relays and contacts of said indication relays which when closed indicate that the stretch is unoccupied, means rendering a control code governed by the operated lever effective to operate the signal control relay which such code controls to its signal clearing position only if transmitted when the associated signal clearing relay is energized, means controlled by the directional relay in the position designating the corresponding trafiic direction for energizing such signal clearing relay upon the initiation of such code, a stick. circuit for maintaining such signal clearing relay energized following the transmission of such. control code, means for automatically restoring said signal control relay to normal when a train governed by the signal cleared by such control code enters the stretch, and means responsive to an indication code indicating that a train governed by the signal cleared by such code has entered the stretch for opening said stick circuit.

10. In combination with a stretch of single track railway having an entering signal at each end governed by traffic conditions in the stretch and by a signal control relay controlled by a signal lever at a central ofiice, a code system for transmitting manually initiated control codes to operate said control relays in accordance with the positions of said levers and for transmitting indication codes to operate indication relays at the ofiice reflecting the condition of occupancy of the stretch and the condition of the signals and of their control relays, a two position directional relay for designating the direction of traffic movements, a signal clearing relay for. each signal, circuits closed in response to the operation of either signal lever when the other signal lever is normal for operating said directional relay to a position designating the direction of trafficgoverned by the operated lever, said circuits including back contacts of both signal clearing relays and contacts of said indication relays which when closed indicate that the stretch is unoccuplied,-means rendering a control code governed by the operated lever effective to operate the signal control relay which such code controls to its signal clearing position only if transmitted when the associated signal clearing relay is energized, means controlled by the directional relay in the position designating the corresponding traffic direction for energizing such signal clearing relay upon the initiation of such code, a stick circuit for maintaining such signal clearing relay energized following the transmission of such control code, a release relay, means for energizing said relay. upon the transmission of a control code if said signal clearing relay is energized but the associated signal lever has been restored to normal to render such code effective to restore the cleared signal manually to stop, means for maintaining said release relay energized only as long as said signal clearing relay is energized andsaid signal ever remains in its normal position, means controlled by an indication code which indicates the occupancy of said stretch for opening the stick circuit for the energized signal clearing relay, and means controlled by an indication code received when said release relay is energized which does not indicate the occupancy of said stretch for opening the stick circuit for the energized signal clearing relay only ifsuch indication code indicates that the corresponding signal has been restored to stop and that its control relay is in its normal position.

11. In combination with a stretch of single track railway equipped with a reversible signaling system controlled by trafiic conditions in the stretch, an entering signal at each end of the stretch controllable by said signaling system and by a signal control relay, a hand throw switch in said stretch having an electric lock, manually operable means for energizing said lock to unlock said switch, said means being rendered effective when said signaling system is divided into two portions which extend from the switch location to the two ends of the stretch and said portions are set up for movement in opposite directions away from the switch location, and jointly indicate at such location that the entirestretch is unoccu- 32 pied, a signal lever and a signal clearing relay for each signal, and a switch lever for the switch, a code system for transmitting control codes to the ends of the blocks to govern said signaling system and said signal control relays, a starting button for each signal lever effective when such lever is reversed to cause the energization of the associated signal clearing relay and the transmission of codes by which the signal control relay for the signal which such lever controls is operated to its signal clearing position and said signaling system is set up in the direction for clearing such signal, means responsive to the operation of said switch lever for preventing the energization of either signal clearing relay and for causing the transmission of control codes for setting up said signaling system as required for the release of said electric lock, means controlled by each signal clearing relay when released for preventing the control of the corresponding signal control relay by codes transmited by switch lever operation regardless of the position of the corresponding signal lever, and means controlled by each signal clearing relay when energized for preventing the code control of said signaling system as required for the release of said electric a repeating relay for the switch, all located at a control oifice, a reversible signaling system arranged to be energized at either end of the stretch to control the signal at the other end in accordance with trafiic conditions in the stretch, means controlled from the office for reversing the direction of said signaling system eifective only when the stretch is unoccupied and said repeating and signal clearing relays are released, a circuit for energizing each signal clearing relay controllable by its lever provided the corresponding traffic direction is established and said repeating relay is released, means for controlling the signal for the corresponding direction in accordance with the condition of said signaling system and the position of its lever rendered effective upon the energization of the associated signal clearing relay, means for energizing said repeating relay in response to the operation of said switch lever effective only when both signal clearing relays are released, means controlled by said repeating relay when energized for energizing said signaling system at both ends, and means at the switch;

location controllable by said signaling system when energized at both ends for releasing said electric lock providedthe stretch is unoccupied.

13. In combination with a stretch of single track railway having entering and leaving signals at each end, a code system of communication having a station at each end of the stretch and means at a control oilice for transmitting codes to said stations to govern the clearing of said signals, a

reversible signaling system for controlling one of said entering signals or the other, according to the direction established thereby, in accordance with trafiic conditions in said stretch, a manually operable signal lever and a code starting button at the oiiice for each station, means responsive to the operation of each starting button for initiating the transmission of a code for controlling the entering or leaving signal at the corresponding station in accordance with the position of the signal lever for such station,

means efiective under selected conditions for initiating the transmission of a code to one station to effect the reversal of said signaling system in response to the operation of the starting button for the other station for clearing the entering signal at said other station, the transmission of such code occurring only if the trailic direction established by said signaling system at the time is the opposite to that which is required in order to clear the entering signal at said other station, and means including a signal clearing relay for each leaving signal controlled jointly by the signal lever for the corresponding station and by the associated starting button for rendering each code transmitted to the corresponding station effective to control said leaving signal if and only if such code is initiated by the operation of said associated starting button.

14. Direction selecting apparatus for a stretch of railway track equipped with a reversible signaling system having an entering signal at each end with a control relay for clearing such signal in accordance with traific conditions in said stretch as manifested by said signaling system when set up in the corresponding direction, together with means for establishing control channels between a central office and stations at the ends of the stretch for the manual control of said signal control relays and of said signaling system, and for also establishing indication channels controlled by said signaling system for indicating traflic conditions at said office, in combination, electroresponsive means at said oifice for designating the direction of traflic movements and for at times reversing said signaling system, :a signal clearing relay at the office for each entering signal effective when operated to establish the channel over which the control relay for such signal is controlled, manually controllable means governed by said electroresponsive means for selectively operating that one of said signal clearing relays which is associated with the entering signal for the direction designated by said electroresponsive means, means for operating the control relay controlled over said channel to its signal clearing position, means controlled by said signaling system for automatically restoring said signal control relay and said signal clearing relay to normal when a train governed by the signal controlled thereby enters the stretch, and manually controllable means for operating said electroresponsive means to change the designated traflic direction efiective only when said signaling system indicates that the stretch is unoccupied and both signal clearing relays occupy their normal positions.

HENRY S. YOUNG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,215,407 Phinney Sept. 17, 1940 2,326,991 Young Aug. 17, 1943 2,420,579 Young May 13, 1947 

